The invention relates to a lamp of the type having a light source including a bulb having a pair of outer leads extending therefrom, a glass envelope surrounding the light source, and a glass stem fixed to the glass envelope. A pair of input leads sealed in the glass stem are electrically connected to the outer leads of the light source. More particularly, the invention relates to a lamp having a protective shroud surrounding the light source.
U.S. Pat. No. 5,670,840 discloses a lamp having a tungsten halogen light source with a filament connected to electrodes connected to metal foils in pinches at opposite ends of a bulb, and outer leads connected to the foils. The outer leads are welded to mounting legs sealed in the glass stem, the mounting legs serving as input leads. One of the mounting legs supports a tubular shroud of glass or quartz which surrounds the light source and protects the glass envelope from fragments in the event of bulb failure. The shroud is fixed to the mounting leg by means of glass connector brackets adjacent opposed open ends of the tube.
The lamp described in U.S. Pat. No. 5,670,840 requires connecting the shroud to a mounting leg at two places by relatively fragile glass connections, subsequently welding the outer leads of the light source to the mounting legs, followed by sealing the mounting leg to the stem.
U.S. Pat. No. 4,888,517 in FIG. 6 discloses a metal halide light source having a pair of electrodes connected to metal foils in a pinch at one end of the bulb, and side-by-side outer leads connected to the foils. The outer leads are welded to input leads sealed in the glass stem. A glass shroud surrounds the light source, the shroud having a cylindrical wall, an open end toward the stem, and an opposed closed end. The shroud is supported by mounting legs which are also welded to respective input leads, the legs being fixed to metal straps surrounding the shroud adjacent respective ends. While the closed end of the shroud provides additional protection for the envelope in the event of bulb failure, multiple welding steps are required to connect the light source to the input leads and to complete the shroud support. Further, since it is necessary to support the shroud by means of a strap adjacent the closed end, the corresponding leg must be loaded against the lamp envelope for stability.
It would be desirable to provide a unified mount structure for supporting the light source, and further to provide simplified and reliable means for positioning a protective shroud about the light source.